Field of the Invention
The invention relates to an interface circuit for speed regulation in an isolated manner and an electrical appliance system comprising the same.
Description of the Related Art
Electrical appliance systems such as central air conditioning systems, ventilation systems, and washing machine systems include a plurality of electronically commutated motors (ECM). Conventionally, the speed of the ECM is regulated using between 0 and 10 V analog voltage. The ECM controller and the speed controller are not common-grounded, as shown in FIG. 1, as a result, the ECM is unable to directly read the voltage. To solve this, signal isolation transmission using linear optocouplers and serial communication using specific communication protocols have been employed, however, both ways are expensive and complex in use.